Ionic liquids, functionalized particulates, and fluoropolymer composites

ABSTRACT

The present invention relates to (i) novel fluoroionic compounds capable of dispersing particulate filler compositions into a fluoropolymer; (ii) novel particulate compositions in which particulates are surface-functionalized with a fluoroionic compound; (iii) fluoropolymer composite materials containing the surface-functionalized particulates of (ii) incorporated into a fluoropolymer; (iv) crosslinked versions of (iii); v) methods for producing the crosslinked material of (iv); and (vi) articles of manufacture containing the compositions (iii) and (iv).

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a divisional application of U.S. patent applicationSer. No. 12/936,330 filed on Oct. 4, 2010, which is a National StageEntry of International Application No. PCT/US09/39585 filed on Apr. 6,2009, which claims the benefit of U.S. Provisional Application No.61/042,438 filed on Apr. 4, 2008.

This invention was made with government support under grant numberDMR0454887 awarded by the National Science Foundation. The governmenthas certain rights in the invention.

FIELD OF THE INVENTION

The present invention relates to novel ionic liquids, functionalizedparticulates, and fluoropolymer composites incorporating thefunctionalized particulates.

BACKGROUND OF THE INVENTION

Fluoropolymer materials are used in printing rollers (e.g., paper feedrollers) commonly used in photocopying machines and printers. Thepreference for fluoropolymer materials for this purpose is primarily dueto the known chemical inertness, elasticity, and low surface tension ofthis class of polymers. In particular, their low surface tension endowsthem with the necessary property of being non-sticking (i.e., releasing)when feeding or directing paper.

However, fluoropolymer materials typically suffer from numerous seriousdrawbacks. First, the required elasticity diminishes over time with use.This process, also known as creeping, eventually renders a printingroller unusable. This vulnerability of the printing roller is very oftenthe first occurrence of malfunction of a photocopier. Since replacing aprinting roller can be troublesome and expensive, it is not unusual thata photocopier with this problem is discarded in favor of a newphotocopier. The time and effort directed to repairing a malfunctioningphotocopier, or the cost of purchasing a new one, pose seriousinconveniences to the consumer.

At least one of the causes believed to contribute to loss of elasticityof fluoropolymer materials is the low thermal conductivity typical forthis class of polymers. The low thermal conductivity causes thefluoropolymer materials to operate at higher temperatures. This quickensthe loss of elasticity, which in turn severely shortens its usefullifetime.

Though it is generally known in the art to incorporate filler materialinto polymers to alter their properties, this practice is severelyhampered in the case of fluoropolymers due to the incompatibility offluoropolymers with most other materials, particularly filler materials.Because of this incompatibility, filler materials typically agglomerateand remain predominantly non-dispersed in a fluoropolymer matrix. Thisagglomeration severely restricts the efficacy of the filler in afluoropolymer matrix.

Accordingly, there remains a need in the art for improving theproperties and increasing the usable lifetime of fluoropolymer materialswhile retaining their elastic and low surface tension properties.

SUMMARY OF THE INVENTION

These and other objectives, as will be apparent to those having ordinaryskill in the art, have been achieved by providing (i) novel fluoroioniccompounds capable of dispersing particulate filler compositions into afluoropolymer; (ii) novel particulate compositions in which particulatesare surface-functionalized with a fluoroionic compound; (iii)fluoropolymer composite materials containing the surface-functionalizedparticulates of (ii) incorporated into a fluoropolymer; (iv) crosslinkedversions of (iii); v) methods for achieving the crosslinked material of(iv); and (vi) articles of manufacture from (iii) and (iv).

In a first aspect, the invention is directed to fluoroionic compounds ofthe formula

wherein R¹ and R³ are, independently, hydrocarbon linking groups havingat least one carbon atom, and optionally including one or morenon-fluoro heteroatoms or heteroatom-containing groups; R² is either ahydrogen atom, or a fluoro-substituted hydrocarbon group having at leastone carbon atom and at least one fluorine atom and optionally includingone or more non-fluoro heteroatoms or heteroatom-containing groups, or aheteroatom-containing group only when m is 1; R⁴ is a fluoro-substitutedhydrocarbon group having at least one carbon atom and at least onefluorine atom and optionally including one or more non-fluoroheteroatoms or heteroatom-containing groups; the subscripts m and p areindependently 0 or 1, where a value of 0 for a subscript represents theabsence of a group to which the subscript is appended, and a value of 1represents the presence of a group to which the subscript is appended;X^(−r) represents an anion with negative charge −r, where r is a valueof 1, 2, or 3; and the subscripts a and b are positive integers suchthat a=b×r.

In a second aspect, the invention is directed to asurface-functionalized particulate composition containing a particulatehaving adhered to its surface an ionic compound of the general formula

wherein M represents a ring or ring system containing at least onenitrogen atom in the ring or ring system; R^(a) is a hydrocarbon linkinggroup bound to a nitrogen atom of M and having at least one carbon atom,and optionally including one or more non-fluoro heteroatoms orheteroatom-containing groups; R^(b) is a fluoro-substituted hydrocarbongroup having at least one carbon atom and at least one fluorine atom andoptionally including one or more non-fluoro heteroatoms orheteroatom-containing groups; the subscript v is 0 or 1, where a valueof 0 for a subscript represents the absence of a group to which thesubscript is appended, and a value of 1 represents the presence of agroup to which the subscript is appended; the subscript w is a positiveinteger representing the number of —(R^(a))_(v)—R^(b) units bound to anequal number of ring nitrogen atoms; +c represents a positive charge ofmagnitude c having a value of at least 1 and equal to the number of ringnitrogen atoms bound to —(R^(a))_(v)—R^(b) units; X^(−r) represents ananion with negative charge −r, where r is a value of 1, 2, or 3; and thesubscripts b and d are integers such that c×d=b×r.

In more specific embodiments, the particulate has adhered to its surfacea fluoroionic compound according to formula (1) above, or a fluoroioniccompound of the general formula

wherein R³ is a hydrocarbon linking group having 1 to 6 carbon atoms; R⁴is a fluoro-substituted hydrocarbon group having 1 to 30 carbon atomsand at least one fluorine atom; R⁵ is a hydrocarbon group having 1 to 6carbon atoms; the subscript p is 0 or 1, where a value of 0 for asubscript represents the absence of a group to which the subscript isappended, and a value of 1 represents the presence of a group to whichthe subscript is appended; X^(−r) represents an anion with negativecharge −r, where r is a value of 1, 2, or 3; and the subscripts a and bare positive integers such that a=b×r.

In a third aspect, the invention is directed to fluoropolymer compositematerials that contain the above-described particulate compositionsincorporated into a fluoropolymer. In a particular embodiment, thefluoropolymer composite material includes crosslinking, i.e., by thepresence of crosslinked bonds.

In a fourth aspect, the invention is directed to a method forincorporating crosslinking into a fluoropolymer composite material. Themethod includes reacting crosslinkable groups residing on afluoropolymer and/or surface of a particulate composition when both thefluoropolymer and particulate composition are in a combined state duringthe reacting step. The crosslinking can be made to occur betweenfluoropolymer crosslinkable and particulate crosslinkable groups, orbetween fluoropolymer crosslinkable groups, or between particulatecrosslinkable groups, or any combination thereof.

In a fifth aspect, the invention is directed to an article ofmanufacture constructed of a material containing the fluoropolymercomposite material described above. The article can be, for example, aprinting roller, tube, hose, sheet, fitted cover, protective cover,sleeve, film, block, ring, ball, part of an electrical component, orpart of a medical device.

As shown, the invention advantageously provides a fluoropolymercomposite material with improved thermal characteristics and a resultinglonger usable life. The invention also advantageously provides newfluoroionic compounds and particulate compositions useful for, interalia, synthesizing the fluoropolymer composites.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1. General schematic showing a preferred method for synthesis offluoroionic liquids.

FIG. 2. A schematic representation of π-stacking arrangement of ionicliquids on a multiwalled carbon nanotube (MWCNT) surface functionalizedwith ionic liquids, also known as an iMWCNT.

FIG. 3 A schematic representation of a preferred method for thepreparation of a nanocomposite formed by incorporating an ionicliquid-functionalized carbon nanotube (iMWCNT) in a fluoropolymer matrix(FEP). The resulting nanocomposite is referred to as an iMWCNT/FEPnanocomposite.

FIG. 4 A schematic representation of a preferred method for thepreparation of acyl chloride-functionalized MWCNT and its reaction withan aminoalkenyl compound to form a chemical-grafted MWCNT (i.e., agMWCNT) having an exposed vinyl group.

FIG. 5 A schematic representation of a preferred method for thepreparation of a fluorinated carbon nanotube by chemical reaction of anacyl chloride-functionalized MWCNT with an amino-functionalizedfluoro-substituted compound.

FIG. 6 A schematic representation showing a preferred method for surfacemodification and functionalization of a fluoropolymer by radiationgrafting using an amino-vinyl grafting compound of the formulaNH₂(CF₂)_(n)CH═CH₂.

FIG. 7 A schematic representation showing a preferred method for surfacemodification and functionalization of a fluoropolymer by radiationgrafting using a hydroxyl-vinyl grafting compound of the formulaHO(CF₂)_(n)CH═CH₂.

FIG. 8 Process flow chart showing a preferred method for the preparationof a crosslinked nanocomposite by a dual cross-linking system using UVand thermal curing.

FIG. 9 A schematic representation showing a preferred method for thepreparation of a crosslinked fluoropolymer nanocomposite by crosslinkingvinyl groups in the fluoropolymer and carbon nanotubes by use of a dualUV-thermal curing process.

FIG. 10 A schematic representation showing a preferred method for thepreparation of a fluoropolymer nanocomposite elastomer containingvinyl-functionalized iMWCNT by use of a dual UV-thermal curing process.

FIG. 11 A schematic representation showing a preferred method for thepreparation of a crosslinked fluoropolymer nanocomposite by a methodwherein carboxyl-functionalized and amino-functionalized carbonnanotubes are chemically crosslinked to form amide crosslinking bonds.

FIG. 12 A schematic representation showing a preferred method for thepreparation of a crosslinked fluoropolymer nanocomposite by a methodwherein carboxyl-functionalized and hydroxyl-functionalized carbonnanotubes are chemically crosslinked to form ester crosslinking bonds.

DETAILED DESCRIPTION OF THE INVENTION

In a first aspect, the present invention is directed to a new class ofionic compounds containing fluorine substitution of hydrogen atoms(i.e., fluoroionic compounds). The ionic compounds contain animidazolium ring with a charge of +1. The various applications to whichthese ionic compounds can be useful include, for example, their use asconductive electrolytes, antistatic agents, non-volatile andenvironmentally friendly solvents, absorbents, and gas storagechemicals.

By one embodiment, the ionic compounds are according to the formula:

In formula (1), R¹ and R³ can be, independently, hydrocarbon linkinggroups each having at least one carbon atom. In a first embodiment, thehydrocarbon linking groups are composed solely of carbon and hydrogen.

The hydrocarbon linking groups can have a maximum of, for example, 30carbon atoms for most applications. In specific embodiments, thehydrocarbon linking groups can preferably contain within about 1 to 10,1 to 8, or 1 to 6 carbon atoms. In other embodiments, the hydrocarbonlinking groups can preferably contain 2 to 10, 2 to 8, or 2 to 6 carbonatoms.

The hydrocarbon linking groups of R¹ and R³ can be saturated andstraight-chained, i.e., straight-chained alkylene linking groups. Someexamples of suitable straight-chained alkylene linking groups includethose described by the formula —(CH₂)_(t)— wherein t is at least 1 andpreferably not more than about 30 for most applications, and morepreferably not more than about 6 when applied as ionic liquids. Someexamples of straight-chained alkylene linking groups include methylene(—CH₂—), ethylene (—CH₂CH₂—), trimethylene (—CH₂CH₂CH₂—), tetramethylene(—CH₂CH₂CH₂CH₂—), pentamethylene (—CH₂CH₂CH₂CH₂CH₂—), and hexamethylene(—CH₂CH₂CH₂CH₂CH₂CH₂—).

The hydrocarbon linking groups of R¹ and R³ can alternatively besaturated and branched, i.e., branched alkylene linking groups. Someexamples of suitable branched alkylene linking groups include —CH(CH₃)—,—C(CH₃)₂—, —CH₂CH(CH₃)—, —CH₂C(CH₃)₂—, —CH(CH₃)C(CH₃)₂—,—C(CH₃)₂C(CH₃)₂—, —CH₂CH(CH₃)CH₂—, and —CH₂C(CH₃)₂CH₂—, where groups inparentheses are not directly engaged in linking, but attached to alinking carbon atom.

The hydrocarbon linking groups of R¹ and R³ can alternatively besaturated and cyclic, i.e., cycloalkylene linking groups. Some examplesof cycloalkylene linking groups include 1,2-cyclopentadiyl,1,2-cyclohexadiyl, and 1,4-cyclohexadiyl.

The hydrocarbon linking groups of R¹ and R³ can alternatively beunsaturated. By being unsaturated, the linking groups have a minimum ofone carbon-carbon double or triple bond. For example, the linking groupscan be straight-chained, i.e., straight-chained alkenyl or alkynyllinking groups. Some examples of such groups include —CH═CH—,—CH═CHCH₂—, —CH₂CH═CHCH₂—, —CH₂CH₂CH═CH—, —C≡C—, and —CH₂C≡CCH₂—. Thelinking groups can be, in addition, branched, i.e., branched alkenyl oralkynyl linking groups. Some examples of such groups include—C(CH₃)═CH—, —C(CH₃)═C(CH₃)—, —CH═C(CH₃)CH₂—, —C(CH₃)═CHCH₂—,—C(CH₃)═C(CH₃)CH₂—, —CH₂C(CH₃)═CHCH₂—, —CH₂C(CH₃)═C(CH₃)CH₂—,—CH(CH₃)C≡CCH₂—, and —CH(CH₃)C≡CCH(CH₃)—. An unsaturated linking groupcan also be cyclic, such as, for example, cyclohex-2-en-1,4-diyl orcyclohex-2,5-diene-1,4-diyl. The cyclic unsaturated linking group canalso be an aromatic linking ring or ring system, such as, for example,1,2-phenylene, 1,4-phenylene, 2,6-dimethyl-1,4-phenylene,4,4′-biphenylene, 4,4′-dimethylene-1,1′-biphenyl (—CH₂—C₆H₄—C₆H₄—CH₂—),diphenylmethane-4,4′-diyl (—C₆H₄—CH₂—C₆H₄—), stilbenzyl(—C₆H₄—CH═CH—C₆H₄—), and divinylenephenylene (—CH═CH—C₆H₄—CH═CH—).

By another embodiment, the hydrocarbon linking groups R¹ and R³ caninclude one or more non-fluoro heteroatoms or heteroatom-containinggroups. Some examples of such heteroatoms include oxygen (O), nitrogen(N), and sulfur (S). In one instance, a heteroatom interrupts acarbon-carbon link in the hydrocarbon linking group. Some examples ofinterrupting heteroatoms include —O—, —NH—, —N═, or —S—. The heteroatomscan also interrupt the hydrocarbon chain in a repetitive manner, such asin linking groups of the form —(CH₂E)_(t)—, —(CH₂CH₂E)_(t)—, or—(CH₂CH₂CH₂E)_(t)— where E represents O, S, or NH and t is greater than1 and up to, for example, 10, 20, or a higher number of units. Inanother instance, a heteroatom substitutes a hydrogen atom of thehydrocarbon linking group. Some examples of substituting heteroatomsinclude —OH, —NH₂, —SH, and Cl.

A heteroatom-containing group contains at least one heteroatom bound toone or more atoms other than hydrogen. In one instance, theheteroatom-containing group interrupts a carbon-carbon link in thehydrocarbon linking group. Some examples of interruptingheteroatom-containing groups include carbonyl —C(O)—, carboxy —C(O)O—,amido —C(O)NH—, urea —NHC(O)NH—, carbamate —NHC(O)O—, sulfoxide —S(O)—,sulfonyl —S(O)₂—, and diazene —N═N—. In another instance, theheteroatom-containing group substitutes a hydrogen atom of thehydrocarbon linking group. Some examples of substitutingheteroatom-containing groups include aldehyde (e.g., —C(O)H), ketones(e.g., —C(O)CH₃), carboxylic acid —C(O)OH, esters (e.g., —C(O)OCH₃),amides (e.g., C(O)NH₂ or C(O)NH(CH₃)), ethers (e.g., —OCH₃), substitutedamines (e.g., —NH(CH₃) or —N(CH₃)₂), nitrile (—CN), nitro (NO₂),sulfonate (—SO₃ ⁻), carboxylate (—CO₂ ⁻).

The R¹ and R³ hydrocarbon linking groups, described above, can bepresent or absent as indicated by the appended subscripts m and p,respectively. The subscripts m and p are independently 0 or 1, where avalue of 0 for a subscript represents the absence of a group to whichthe subscript is appended, and a value of 1 represents the presence of agroup to which the subscript is appended.

In formula (1), R² can be a hydrogen atom. When R² is a hydrogen atom,and when R¹ is present (m=1) without heteroatom substitution, then—R¹—R² represents a hydrocarbon group. The hydrocarbon group can bederived from any of the R¹ hydrocarbon linking groups described abovewhere one end of the linking group is connected to a hydrogen atom.

For example, —R¹—R² can represent a saturated straight-chainedhydrocarbon group. Some examples of such groups include methyl, ethyl,n-propyl, n-butyl, n-pentyl, n-hexyl, n-heptyl, n-octyl, n-nonyl,n-decyl, and the like. Alternatively, —R¹—R² can represent a saturatedbranched hydrocarbon group. Some examples of such groups includeisopropyl, isobutyl, sec-butyl, t-butyl, 2-pentyl, 3-pentyl,3-methylbutyl(isopentyl), 2,2-dimethylpropyl(neopentyl),1,2-dimethylpropyl, 2-methylbutyl, 3-methylpentyl, 4-methylpentyl, andthe like. Alternatively, —R¹—R² can represent a saturated cyclichydrocarbon group. Some examples of such groups include cyclopropyl,cyclobutyl, cyclopentyl, cyclohexyl, and cycloheptyl.

Alternatively, —R¹—R² can represent an unsaturated straight-chainedhydrocarbon group. Some examples of such groups include vinyl,2-propen-1-yl, 3-buten-1-yl, 4-penten-1-yl, 5-hexen-1-yl, 6-hepten-1-yl,2-buten-lyl, 2-penten-1-yl, 3-penten-1-yl, 2,4-pentadienyl,2,4,6-heptatrienyl, ethynyl, 2-propyn-1-yl (propargyl), 3-butyn-1-yl,4-pentyn-1-yl, 2-butyn-1-yl, and the like. Alternatively, —R¹—R² canrepresent an unsaturated branched group. Some examples of such groupsinclude propen-2-yl, 1-buten-2-yl, 1-buten-3-yl, 1-buten-2-methyl-3-yl,1-buten-3-methyl-3-yl, 2-buten-2-methyl-3-yl.

The group —R¹—R² can alternatively represent an unsaturated cyclichydrocarbon group. Some examples of such groups include1-cyclopenten-1-yl, 1-cyclopenten-3-yl, 1-cyclopenten-4-yl,3,4-dimethyl-3-cyclopenten-1-yl, 2,4-cyclopentadien-1-yl,1-cyclohexen-1-yl, 1-cyclohexen-3-yl, 1-cyclohexen-4-yl, and2,5-cyclohexadien-1-yl. The unsaturated cyclic hydrocarbon group canalso be an aromatic ring, such as phenyl.

The group —R¹—R² can also represent a ring system. The ring systemincludes more than one ring, wherein the rings are directly orindirectly connected. When the rings are connected, they can be, forexample, fused, connected by a bond, or form a bicyclic, tricyclic, orhigher ring system. Some examples of hydrocarbon fused ring systemsinclude naphthalenyl, anthracenyl, phenanthrenyl, and indenyl. Anexample of a bond-connected ring system includes biphenyl. Some examplesof hydrocarbon bicyclic ring systems includebicyclo[4.4.0]decanyl(decalinyl), bicyclo[2.2.1]heptanyl(norbornyl), andnorbornenyl.

In another embodiment, R² is a hydrogen atom, and R¹ is present (m=1)and includes insertion or hydrogen-atom substitution by one or moreheteroatoms. In such a case, —R¹—R² represents a heteroatom-substitutedhydrocarbon group. The heteroatom-substituted group can be, for example,any of the heteroatom-substituted linker groups R¹, as described above,wherein the capping group R² is a hydrogen atom. Theheteroatom-substituted group can also be, for example, any of thehydrocarbon groups described above when R¹ is a hydrocarbon linkergroup, wherein the groups have been modified by insertion orhydrogen-atom substitution by one or more heteroatoms. For example, thehydrocarbon rings and ring systems described above can also include oneor more ring heteroatoms or heteroatom-containing groups. For the caseof rings, the heteroatoms more commonly include the heteroatoms N, O,and S. Some examples of heteroatom-containing rings and ring systemsinclude pyrrolyl, pyrrolidinyl, imidazolyl, pyrazolyl, piperidinyl,N-methylpiperidinyl, pyridinyl, piperazinyl, pyrazinyl, pyrimidinyl,triazinyl, oxazolyl, morpholinyl, thiopheneyl, indolyl, purinyl, andfuranyl.

In formula (1), R² can also be a fluoro-substituted hydrocarbon grouphaving at least one carbon atom and at least one fluorine atom. For manyapplications, particularly when the ionic compound is desired to be anionic liquid or viscous solid, a maximum carbon number of about 30 issufficient. The fluoro-substituted hydrocarbon group of R² is properlydescribed by reference to the hydrocarbon groups described above for—R¹—R² and making the modification that at least one hydrogen atom ofany of the classes or specific examples described therein be substitutedby a fluorine atom.

In a first embodiment, the fluoro-substituted hydrocarbon group of R²does not contain any non-fluoro heteroatoms. Some examples of such R²groups include fluoromethyl (—CH₂F), difluoromethyl (—CHF₂),trifluoromethyl (i.e., perfluoromethyl, CF₃), fluoroethyl (—CH₂CH₂F or—CHFCH₃), difluoroethyl (—CH₂CHF₂ or CHFCH₂F or —CF₂CH₃), trifluoroethyl(—CH₂CF₃ or —CHFCHF₂ or CF₂CH₂F), tetrafluoroethyl (—CHFCF₃ or—CF₂CHF₂), perfluoroethyl (—CF₂CF₃), fluoropropyl (—CH₂CH₂CH₂F or—CH(CH₃)CH₂F or —CHFCH₂CH₃), difluoropropyl (e.g., —CH₂CHFCHF),trifluoropropyl (e.g., —CHFCHFCH₂F or —CH(CF₃)CH₃), tetrafluoropropyl(e.g., —CHFCHFCHF₂), pentafluoropropyl (e.g., —CHFCHFCF₃),hexafluoropropyl (e.g., —CHFCF₂CF₃ or —CH(CF₃)₂), perfluoropropyl (e.g.,—CF₂CF₂CF₃ or —CF(CF₃)₂), perfluorobutyl (—(CF₂)₃CF₃ or —CF(CF₃)CF₂CF₃or —CF₂CF(CF₃)₂ or —C(CF₃)₃), perfluoropentyl (e.g., —(CF₂)₄CF₃),perfluorohexyl (e.g., —(CF₂)₅CF₃), perfluoroheptyl, perfluorooctyl,perfluorononyl, perfluorodecyl, perfluoroundecyl, perfluorododecyl,perfluorotridecyl, perfluorotetradecyl, perfluoropentadecyl,perfluorohexadecyl, perfluoroheptadecyl, perfluorooctadecyl, fluorovinyl(—CH═CHF or —CF═CH₂), difluorovinyl (—CH═CF₂ or —CF═CHF), trifluorovinyl(—CF═CF₂), difluoropropenyl (e.g., —CF═CF(CH₃)), trifluoropropenyl(e.g., —CH═CH(CF₃)), pentafluoropropenyl (e.g., —CF═CF(CF₃),—C(CF₃)═CF₂, or —CF₂CF═CF₂), hexafluorobutenyl (e.g.,—CH₂C(CF₃)═CH(CF₃)), perfluorobutenyl (e.g., —CF₂CF₂CF═C—F₂ or—CF₂CF═CFCF₃), branched hexafluoropentenyl (e.g., —CH₂C(CF₃)═CH(CF₃) or—CH₂—CH═C(CF₃)₂)), trifluoromethylethynyl (—C≡C—CF₃),trifluoromethylpropargyl (e.g., —CH₂C≡C—CF₃), pentafluoro-1,3-butadienyl(—CF═CFCF═CF₂), fluorocyclopentyl, fluorocyclohexyl, difluorocyclohexyl,perfluorocyclohexyl, fluorophenyl, difluorophenyl, trifluorophenyl,tetrafluorophenyl, pentafluorophenyl, trifluoromethylphenyl, andbis(trifluoromethyl)phenyl.

In a second embodiment, the fluoro-substituted hydrocarbon group of R²contains one or more non-fluoro heteroatoms or heteroatom-containinggroups. Some examples of such R² groups include —OCF₃, —OCF₂CF₃,—(OCF₂)_(x)R, —(OCF₂CF₂)_(x)R, —(OCF(CF₃)CF₂)_(x)R, —(CF₂CF₂O)_(x)R,—(CF(CF₃)CF₂O)_(x)R, —[CF₂CF(OR)]_(x)R, where x is preferably from about1 to 20 and R is independently hydrogen or any of the hydrocarbon orfluoro-substituted hydrocarbon groups described above, —CF₂OCF₃,—CF₂CF₂OCF₃, —CF₂CF₂OCF₂CF₃, —OC₆F₅, —C₆F₄OR, —OCF═CF₂, —OCH₂—CF═CF₂,—OCH₂CH(CF₃)CH₃, —NH(CF₃), —N(CF₃)₂, —NH(CF₂)₇CF₃, —N[(CF₂)₇CF₃]₂,—NH(CF₂CF₂OR), —N(CF₂CF₂OR)₂, —N⁺(CF₃), —S(O)₂CF₃, —CF₂S(O)₂CF₂CF₃,—N═CF₂, 4-fluoropyridinium, 4-trifluoromethylpiperazinyl,4-perfluorooctyl-piperazinium, —Si(CF₃)₃, —Si(OCF₃)₃, —SiR₂(CF₂)₇CF₃,—SiR₂(OCF₃)₂, —CH₂CH₂C(O)OCF₃, —CH₂CH₂C(O)OC₆F₁₀, —CH₂CH₂C(O)OC₆F₅,—SCF₃, and —SCF₂CF₃.

In a particular embodiment, R¹ represents one or more additionalimidazole or imidazolium rings interconnected by one or more linkers,the length and composition of each linker being independent. Forexample, R¹ can represent an imidazolium ring connected indirectly byone of its ring nitrogen atoms through a hydrocarbon linker to the ringnitrogen shown in FIG. 1. Alternatively, R1 can represent for example,two, three, four, or a higher number of imidazole or imidazolium ringseach interconnected by a linker, wherein one of the imidazole ringstherein is connected indirectly by one of its ring nitrogen atomsthrough a hydrocarbon linker to the ring nitrogen atom shown in FIG. 1.R² is any suitable group as described above, that caps the R¹ linkercontaining the one or more imidazole rings.

In formula (1), R² can also simply be a heteroatom-containing group onlywhen m is 1. In this embodiment, R² functions as a heteroatom endcappinggroup in the —R¹—R² combined group, and therefore, the combined group—R¹—R² can aptly be described as an endcapped hydrocarbon group. Theapplicable heteroatom-containing groups have already been describedabove. Some examples of —R¹—R² in this embodiment include —R¹—OH,R¹—NH₂, R¹—NH₃ ⁺, R¹—NH(CH₃), R¹—N(CH₃)₂, R¹—C(O)H, R¹—C(O)OH,R¹—C(O)NH₂, R¹—S(O)₂OH, R¹—CN, R¹—F, R¹—Cl, R¹—Br, R¹—NO₂, R¹—OCN, andR¹—NCO, where R¹ can be any of the substituted or non-substitutedhydrocarbon groups described above.

In one embodiment, the —R¹—R² combined group does not include adichlorophenyl group. In another embodiment, the —R¹—R² combined groupmay include one such group but does not include two dichlorophenylgroups. In another embodiment, the —R¹—R² combined group may include twosuch groups but does not include that the two dichlorophenyl groups areinterconnected by an oxyalkylene spacer, such as —CH₂OCH₂—. In a moreparticular embodiment, the —R¹—R² combined group is not a[2-(2,4-dichlorophenyl)-2-(2,4-dichlorobenzyloxy)]ethyl-1-yl group.

In formula (1), R⁴ is a fluoro-substituted hydrocarbon group having atleast one carbon atom and at least one fluorine atom and optionallyincluding one or more non-fluoro heteroatoms or heteroatom-containinggroups. All of the fluoro-substituted hydrocarbon groups alreadydescribed above for R² are applicable to R⁴ (i.e., R⁴ is aptly describedby all of the fluoro-substituted hydrocarbon groups already describedfor R²). In some embodiments, R⁴ can have a maximum of, for example, 30carbon atoms for most applications. In other embodiments, R⁴ canpreferably contain within about 4 to 12, or 6 to 10, carbon atoms.

X^(−r) represents an anion with negative charge −r, where r typicallyassumes a value of 1, 2, or 3. In order to preserve charge neutrality,the subscripts a and b are positive integers such that a=b×r. Someexamples of suitable counteranions include the halides (e.g., fluoride,chloride, bromide, iodide), PF₆ ⁻, BF₄ ⁻, bistriflimide [(CF₃SO₂)₂N]⁻,triflate (CF₃SO₃ ⁻), tosylate, nitrate, borate, chlorate, perchlorate,bromate, perbromate, iodate, periodate, aluminates, phosphates, sulfate,bisulfate, sulfonates, hydroxide, formate, oxalate, acetate, glycolate,propionate, butyrate, succinate, malonate, fumarate, citrate,terephthalate, phthalate, and glutarate.

In a first embodiment, formula (1) refers to the class of imidazoliumcompounds wherein R¹ and R³ linking groups are absent. A1,3-di-(fluorohydrocarbon) imidazolium subclass of compounds resultswhen R² is a fluorosubstituted hydrocarbon group. Some examples of thesetypes of compounds include the salts of1,3-bis(perfluoromethyl)imidazolium, 1,3-bis(perfluoroethyl)imidazolium,1,3-bis-(perfluorooctyl)imidazolium,1-perfluorooctyl-3-perfluoromethylimidazolium, and1-perfluorooctyl-3-perfluoropropylimidazolium.

A 1-(H)-3-fluorohydrocarbon imidazolium subclass of compounds resultswhen R² is a hydrogen atom. Some examples of these types of compoundsinclude the salts of 1-perfluoromethyl-3-H-imidazolium,1-perfluoroethyl-3-H-imidazolium, 1-perfluoropropyl-3-H-imidazolium,1-perfluorobutyl-3-H-imidazolium, 1-perfluoropentyl-3-H-imidazolium,1-perfluorohexyl-3-H-imidazolium, 1-perfluoroheptyl-3-H-imidazolium,1-perfluorooctyl-3-H-imidazolium, 1-perfluorododecyl-3-H-imidazolium,and 1-perfluorohexadecyl-3-H-imidazolium.

In a second embodiment, formula (1) refers to the class of imidazoliumcompounds wherein R³ remains absent, R¹ is present, and R² is a hydrogenatom. In this class, —R¹—R² represents a hydrocarbon group, andtherefore, this class of compounds represents a1-fluorohydrocarbon-3-hydrocarbon imidazolium class of compounds. Someexamples of these types of compounds include the salts of1-perfluoromethyl-3-methylimidazolium,1-perfluoroethyl-3-methylimidazolium,1-perfluorodecyl-3-methylimidazolium,1-perfluorooctyl-3-propylimidazolium,1-perfluoromethyl-3-isopropylimidazolium,1-perfluorododecyl-3-isopropylimidazolium,1-perfluorooctyl-3-butylimidazolium,1-perfluorooctyl-3-isobutylimidazolium,1-perfluoromethyl-3-vinylimidazolium,1-perfluorobutyl-3-vinylimidazolium,1-perfluorooctyl-3-vinylimidazolium,1-perfluorooctyl-3-allylimidazolium,1-perfluorodecyl-3-(3-butenyl)imidazolium, and1-perfluorooctyl-3-phenylimidazolium.

In a third embodiment, formula (1) refers to the class of imidazoliumcompounds wherein R³ remains absent, R¹ is present, and R² is afluorohydrocarbon group. In this case, —R¹—R² represents a (hydrocarbonlinker)-fluorohydrocarbon group. Therefore, these compounds belong tothe 1-fluorohydrocarbon-3-(hydrocarbon-fluorohydrocarbon) imidazoliumclass of compounds. Some examples of these types of compounds includethe salts of 1-perfluoromethyl-3-(2,2,2-trifluoroethyl)imidazolium,1-perfluoroethyl-3-(2,2,2-trifluoroethyl)imidazolium,1-perfluoroisopropyl-3-(2,2,2-trifluoroethyl)imidazolium,1-perfluoroisobutyl-3-(2,2,3,3,4,4,4-heptafluorobutyl)imidazolium,1-perfluorooctyl-3-(perfluorooctylmethyl)imidazolium,1-perfluoropropyl-3-(3-perfluorododecylpropyl)imidazolium,1-perfluoromethyl-3-(6-perfluoropropylhexyl)imidazolium,1-perfluoropropyl-3-(8-perfluorooctyloctyl)imidazolium, and1-perfluorotetradecyl-3-(6-perfluorooctylhexyl)imidazolium.

In a fourth embodiment, formula (1) refers to the class of imidazoliumcompounds wherein R¹ and R³ are both present and R² is afluorohydrocarbon group. In this class, —R¹—R² and —R³—R⁴ eachindependently represents a (hydrocarbon linker)-fluorohydrocarbon group.Therefore, these compounds belong to the1,3-(hydrocarbon-fluorohydrocarbon)imidazolium class of compounds. Someexamples of these types of compounds include the salts ofbis-1,3-(2,2,2-trifluoroethyl)imidazolium,1-(3-perfluoropropylpropyl)-3-(2,2,2-trifluoroethyl)imidazolium,bis-1,3-(4-perfluoromethylbutyl)imidazolium,bis-1,3-(8-perfluoromethyloctyl)imidazolium,bis-1,3-(3-perfluorooctylpropyl)imidazolium,bis-1,3-(2-perfluorodecylethyl)imidazolium,1-(2,2,2-trifluoroethyl)-3-(12-perfluoroethyldodecyl)imidazolium,1-(3-perfluoromethylpropyl)-3-(3-perfluorooctylpropyl)imidazolium,bis-1,3-(6-perfluorooctylhexyl)imidazolium, andbis-1,3-(2-perfluorotetradecylethyl)imidazolium.

In a fifth embodiment, formula (1) refers to the class of imidazoliumcompounds wherein R¹ and R³ are both present and R² is a hydrogen atom.In this case, —R¹—R² represents a hydrocarbon group. Therefore, thesecompounds belong to the 1-(hydrocarbon-fluorohydrocarbon)-3-hydrocarbonimidazolium class of compounds. A subclass of these compounds can beconveniently described according to formula (3) below.

In formula (3), —R¹—R² has been replaced with R⁵, where R⁵ is ahydrocarbon group. R⁵ preferably contains about 1 to 6 carbon atoms. Thelinking group R³ also preferably contains about 1 to 6 carbon atoms. Thegroup R⁴ is a fluoro-substituted hydrocarbon group, as already definedabove.

Some examples of these types of compounds include the salts of1-(2-fluoroethyl)-3-methylimidazolium,1-(2,2,2-trifluoroethyl)-3-methylimidazolium,1-(2,2,2-trifluoroethyl)-3-ethylimidazolium,1-(2,2,2-trifluoroethyl)-3-ethylimidazolium,1-(2,2,2-trifluoroethyl)-3-propylimidazolium,1-(2,2,2-trifluoroethyl)-3-isopropylimidazolium,1-(2,2,2-trifluoroethyl)-3-butylimidazolium,1-(2,2,2-trifluoroethyl)-3-isobutylimidazolium,1-(3-perfluoroethylpropyl)-3-methylimidazolium,1-(3-perfluorooctylpropyl)-3-methyl imidazolium,1-(3-perfluorodecylpropyl)-3-methylimidazolium,1-(3-perfluorotetradecylpropyl)-3-methylimidazolium,1-(2,2,2-trifluoroethyl)-3-octylimidazolium,1-(2-perfluorotetradecylethyl)-3-isopentylimidazolium,1-(2-perfluoropropylethyl)-3-dodecylimidazolium,1-(3-perfluoroethylpropyl)-3-vinylimidazolium,1-(3-perfluorooctylpropyl)-3-vinyl imidazolium,1-(3-perfluorooctylpropyl)-3-benzyl imidazolium,1-(3-perfluorooctylpropyl)-3-(3-butenyl) imidazolium,1-(3-perfluorooctylpropyl)-3-cyclohexylimidazolium,1-(3-perfluorodecylpropyl)-3-vinylimidazolium,1-(3-perfluorotetradecylpropyl)-3-vinylimidazolium, and1-(2,2,2-trifluoroethyl)-3-(7-octenyl)imidazolium.

Table 1, as shown below, lists numerous exemplary ionic compoundsaccording to the present invention.

TABLE 1 Exemplary compounds of the invention No. Name of ImidazoliumPortion of Compound R¹ R² R³ R⁴ 1 1,3-bis(perfluoromethyl)imidazoliumabsent CF₃ absent CF₃ 2 1-perfluoroethyl-3- absent CF₃ absent CF₂CF₃ 31-perfluorohexyl-3- absent CF₃ absent (CF₂)₅CF₃ 4 1-perfluorooctyl-3-absent CF₃ absent (CF₂)₇CF₃ 5 1-perfluorohexadecyl-3- absent CF₃ absent(CF₂)₁₅CF₃ 6 1,3-bis(perfluoroethyl)imidazolium absent CF₂ absent CF₂CF₃7 1-perfluorobutyl-3- absent CF₂ absent (CF₂)₃CF₃ 81,3-bis(perfluoropropyl)imidazolium absent CF₂ absent CF₂CF₂CF₃ 91-perfluorooctyl-3- absent CF₂ absent (CF₂)₇CF₃ 101,3-bis(perfluorobutyl)imidazolium absent (CF₂ absent (CF₂)₃CF₃ 111-perfluorooctyl-3- absent (CF₂ absent (CF₂)₇CF₃ 121,3-bis(perfluorohexyl)imidazolium absent (CF₂ absent (CF₂)₅CF₃ 131-perfluorooctyl-3- absent (CF₂ absent (CF₂)₇CF₃ 141-perfluorohexadecyl-3- absent (CF₂ absent (CF₂)₁₅CF₃ 151,3-bis(perfluorooctyl)imidazolium absent (CF₂ absent (CF₂)₇CF₃ 161,3-bis(perfluorododecyl)imidazolium absent (CF₂ absent (CF₂)₁₁CF₃ 171,3-bis(perfluorohexadecyl)imidazolium absent (CF₂ absent (CF₂)₁₅CF₃ 181-perfluoromethyl-3-methylimidazolium —CH₂— H absent CF₃ 191-perfluoroethyl-3-methylimidazolium —CH₂— H absent CF₂CF₃ 201-perfluoropropyl-3-methylimidazolium —CH₂— H absent CF₂CF₂CF₃ 211-perfluorobutyl-3-methylimidazolium —CH₂— H absent (CF₂)₃CF₃ 221-perfluorooctyl-3-methylimidazolium —CH₂— H absent (CF₂)₇CF₃ 231-perfluorodecyl-3-methylimidazolium —CH₂— H absent (CF₂)₉CF₃ 241-perfluorododecyl-3-methylimidazolium —CH₂— H absent (CF₂)₁₁CF₃ 251-perfluorohexadecyl-3-methylimidazolium —CH₂— H absent (CF₂)₁₅CF₃ 261-perfluorooctadecyl-3-methylimidazolium —CH₂— H absent (CF₂)₁₇CF₃ 271-perfluoromethyl-3-ethylimidazolium —CH₂CH₂— H absent CF₃ 281-perfluoroethyl-3-ethylimidazolium —CH₂CH₂— H absent CF₂CF₃ 291-perfluorooctyl-3-ethylimidazolium —CH₂CH₂— H absent (CF₂)₇CF₃ 301-perfluorododecyl-3-ethylimidazolium —CH₂CH₂— H absent (CF₂)₁₁CF₃ 311-perfluoromethyl-3-propylimidazolium —(CH₂)₃— H absent CF₃ 321-perfluoroethyl-3-propylimidazolium —(CH₂)₃— H absent CF₂CF₃ 331-perfluorooctyl-3-propylimidazolium —(CH₂)₃— H absent (CF₂)₇CF₃ 341-perfluorododecyl-3-propylimidazolium —(CH₂)₃— H absent (CF₂)₁₁CF₃ 351-perfluoromethyl-3-isopropylimidazolium —C(CH₃)₂— H absent CF₃ 361-perfluoroethyl-3-isopropylimidazolium —C(CH₃)₂— H absent CF₂CF₃ 371-perfluorooctyl-3-isopropylimidazolium —C(CH₃)₂— H absent (CF₂)₇CF₃ 381-perfluorododecyl-3-isopropylimidazolium —C(CH₃)₂— H absent (CF₂)₁₁CF₃39 1-perfluoromethyl-3-butylimidazolium —(CH₂)₄— H absent CF₃ 401-perfluoroethyl-3-butylimidazolium —(CH₂)₄— H absent CF₂CF₃ 411-perfluorooctyl-3-butylimidazolium —(CH₂)₄— H absent (CF₂)₇CF₃ 421-perfluorododecyl-3-butylimidazolium —(CH₂)₄— H absent (CF₂)₁₁CF₃ 431-perfluorohexadecyl-3-butylimidazolium —(CH₂)₄— H absent (CF₂)₁₅CF₃ 441-perfluoromethyl-3-isobutylimidazolium isobutyl H absent CF₃ 451-perfluorooctyl-3-isobutylimidazolium isobutyl H absent (CF₂)₇CF₃ 461-perfluoromethyl-3-t-butylimidazolium t-butyl H absent CF₃ 471-perfluorooctyl-3-t-butylimidazolium t-butyl H absent (CF₂)₇CF₃ 481-perfluoromethyl-3-pentylimidazolium —(CH₂)₅— H absent CF₃ 491-perfluorooctyl-3-pentylimidazolium —(CH₂)₅— H absent (CF₂)₇CF₃ 501-perfluoromethyl-3-isopentylimidazolium isopentyl H absent CF₃ 511-perfluorooctyl-3-isopentylimidazolium isopentyl H absent (CF₂)₇CF₃ 521-perfluorododecyl-3-isopentylimidazolium isopentyl H absent (CF₂)₁₁CF₃53 1-perfluoromethyl-3-hexylimidazolium —(CH₂)₆— H absent CF₃ 541-perfluorooctyl-3-hexylimidazolium —(CH₂)₆— H absent (CF₂)₇CF₃ 551-perfluoromethyl-3-vinylimidazolium vinyl H absent CF₃ 561-perfluoroethyl-3-vinylimidazolium vinyl H absent CF₂CF₃ 571-perfluoropropyl-3-vinylimidazolium vinyl H absent CF₂CF₂CF₃ 581-perfluorobutyl-3-vinylimidazolium vinyl H absent (CF₂)₃CF₃ 591-perfluorooctyl-3-vinylimidazolium vinyl H absent (CF₂)₇CF₃ 601-perfluorodecyl-3-vinylimidazolium vinyl H absent (CF₂)₉CF₃ 611-perfluorododecyl-3-vinylimidazolium vinyl H absent (CF₂)₁₁CF₃ 621-perfluorohexadecyl-3-vinylimidazolium vinyl H absent (CF₂)₁₅CF₃ 631-perfluorooctadecyl-3-vinylimidazolium vinyl H absent (CF₂)₁₇CF₃ 641-perfluoromethyl-3-phenylimidazolium phenyl H absent CF₃ 651-perfluorooctyl-3-phenylimidazolium phenyl H absent (CF₂)₇CF₃ 661-perfluorohexadecyl-3-phenylimidazolium phenyl H absent (CF₂)₁₅CF₃ 671-perfluoromethyl-3-benzylimidazolium benzyl H absent CF₃ 681-perfluorooctyl-3-benzylimidazolium benzyl H absent (CF₂)₇CF₃ 691-perfluorohexadecyl-3-benzylimidazolium benzyl H absent (CF₂)₁₅CF₃ 701-perfluoromethyl-3-(2,2,2- —CH₂— CF₃ absent CF₃trifluoroethyl)imidazolium 71 1-perfluoroethyl-3-(2,2,2- —CH₂— CF₃absent CF₂CF₃ trifluoroethyl)imidazolium 72 1-perfluoropropyl-3-(2,2,2-—CH₂— CF₃ absent CF₂CF₂CF₃ trifluoroethyl)imidazolium 731-perfluorooctyl-3-(2,2,2- —CH₂— CF₃ absent (CF₂)₇CF₃trifluoroethyl)imidazolium 74 1-perfluorododecyl-3-(2,2,2- —CH₂— CF₃absent (CF₂)₁₁CF₃ trifluoroethyl)imidazolium 751-perfluorooctyl-3-(2,2,3,3,3- —CH₂— CF₂CF₃ absent (CF₂)₇CF₃pentafluoropropyl)imidazolium 76 1-perfluorotetradecyl-3-(2,2,3,3,3-—CH₂— CF₂CF₃ absent (CF₂)₁₃CF₃ pentafluoropropyl)imidazolium 771-perfluorooctyl-3-(2,2,3,3,4,4,4- —CH₂— CF₂CF₂CF₃ absent (CF₂)₇CF₃heptafluorobutyl)imidazolium 78 1-perfluorododecyl-3-(2,2,3,3,4,4,4-—CH₂— CF₂CF₂CF₃ absent (CF₂)₁₁CF₃ heptafluorobutyl)imidazolium 791-perfluorooctyl-3- —CH₂— (CF₂)₃CF₃ absent (CF₂)₇CF₃(perfluorobutylmethyl)imidazolium 80 1-perfluorooctyl-3- —CH₂— (CF₂)₇CF₃absent (CF₂)₇CF₃ (perfluorooctylmethyl)imidazolium 811-perfluoromethyl-3-(2- —CH₂CH₂— (CF₂)₃CF₃ absent CF₃perfluorobutylethyl)imidazolium 82 1-perfluoroethyl-3-(2- —CH₂CH₂—(CF₂)₃CF₃ absent CF₂CF₃ perfluorobutylethyl)imidazolium 831-perfluoropropyl-3-(2- —CH₂CH₂— (CF₂)₅CF₃ absent CF₂CF₂CF₃perfluorohexylethyl)imidazolium 84 1-perfluorooctyl-3-(2- —CH₂CH₂—(CF₂)₅CF₃ absent (CF₂)₇CF₃ perfluorohexylethyl)imidazolium 851-perfluoromethyl-3-(3- —(CH₂)₃— (CF₂)₅CF₃ absent CF₃perfluorohexylpropyl)imidazolium 86 1-perfluoroethyl-3-(3- —(CH₂)₃—(CF₂)₇CF₃ absent CF₂CF₃ perfluorooctylpropyl)imidazolium 871-perfluoropropyl-3-(3- —(CH₂)₃— (CF₂)₁₁CF₃ absent CF₂CF₂CF₃perfluorododecylpropyl)imidazolium 88 1-perfluorooctyl-3-(3- —(CH₂)₃—(CF₂)₁₅CF₃ absent (CF₂)₇CF₃ perfluorohexadecylpropyl)imidazolium 89bis-1,3-(2,2,2-trifluoroethyl)imidazolium —CH₂— CF₃ —CH₂— CF₃ 901-(2,2,3,3,3-pentafluoropropyl)-3-(2,2,2- —CH₂— CF₃ —CH₂— CF₂CF₃trifluoroethyl)imidazolium 91 1-(perfluorobutylmethyl)-3-(2,2,2- —CH₂—CF₃ —CH₂— CF₂CF₂CF₃ trifluoroethyl)imidazolium 921-(perfluorooctylmethyl)-3-(2,2,2- —CH₂— CF₃ —CH₂— (CF₂)₇CF₃trifluoroethyl)imidazolium 93 1-(perfluorododecylmethyl)-3-(2,2,2- —CH₂—CF₃ —CH₂— (CF₂)₁₁CF₃ trifluoroethyl)imidazolium 941-(perfluorooctadecylmethyl)-3-(2,2,2- —CH₂— CF₃ —CH₂— (CF₂)₁₇CF₃trifluoroethyl)imidazolium 95 1-(3-perfluorooctylpropyl)-3-(2,2,3,3,3-—CH₂— CF₂CF₃ —(CH₂)₃— (CF₂)₇CF₃ pentafluoropropyl)imidazolium 961-(2-perfluorooctylethyl)-3-(2,2,3,3,3- —CH₂— CF₂CF₃ —CH₂CH₂— (CF₂)₇CF₃pentafluoropropyl)imidazolium 97 1-(2-perfluorooctylethyl)-3- —CH₂—CF₂CF₂CF₃ —CH₂CH₂— (CF₂)₇CF₃ (perfluoropropylmethyl)imidazolium 981-(3-perfluorooctylpropyl)-3- —CH₂— CF₂CF₂CF₃ —(CH₂)₃— (CF₂)₇CF₃(perfluoropropylmethyl)imidazolium 99 1-(2-perfluorooctylethyl)-3- —CH₂—(CF₂)₃CF₃ —CH₂CH₂— (CF₂)₇CF₃ (perfluorobutylmethyl)imidazolium 1001-(perfluorooctylmethyl)-3- —CH₂— (CF₂)₇CF₃ —CH₂— (CF₂)₇CF₃(perfluorooctylmethyl)imidazolium 101 1-(4,4,4-trifluorobutyl)-3-(2-—CH₂CH₂— (CF₂)₃CF₃ —(CH₂)₃— CF₃ perfluorobutylethyl)imidazolium 102bis-1,3-(2-perfluorobutylethyl)imidazolium —CH₂CH₂— (CF₂)₃CF₃ —CH₂CH₂—(CF₂)₃CF₃ 103 1-(2-perfluoropropylethyl)-3-(2- —CH₂CH₂— (CF₂)₅CF₃—CH₂CH₂— CF₂CF₂CF₃ perfluorohexylethyl)imidazolium 104bis-1,3-(2-perfluorohexylethyl)imidazolium —CH₂CH₂— (CF₂)₅CF₃ —CH₂CH₂—(CF₂)₅CF₃ 105 1-(4,4,4-trifluorobutyl)-3-(3- —(CH₂)₃— (CF₂)₅CF₃ —(CH₂)₃—CF₃ perfluorohexylpropyl)imidazolium 106bis-1,3-(3-perfluorooctylpropyl)imidazolium —(CH₂)₃— (CF₂)₇CF₃ —(CH₂)₃—(CF₂)₇CF₃ 107 1-(5-perfluorooctylpentyl)-3-(3- —(CH₂)₃— (CF₂)₇CF₃—(CH₂)₅— (CF₂)₇CF₃ perfluorooctylpropyl)imidazolium 108 bis-1,3-(3-—(CH₂)₃— (CF₂)₁₁CF₃ —(CH₂)₃— (CF₂)₁₁CF₃perfluorododecylpropyl)imidazolium 109 bis-1,3-(3- —(CH₂)₃— (CF₂)₁₅CF₃—(CH₂)₃— (CF₂)₁₅CF₃ perfluoroohexadecylpropyl)imidazolium 110bis-1,3-(7,7,7-trifluoroheptyl)imidazolium —(CH₂)₆— CF₃ —(CH₂)₆— CF₃ 111bis-1,3-(9,9,10,10,10- —(CH₂)₈— CF₂CF₃ —(CH₂)₈— CF₂CF₃pentafluorodecyl)imidazolium 112 bis-1,3-(6- —(CH₂)₆— (CF₂)₁₅CF₃—(CH₂)₆— (CF₂)₁₅CF₃ perfluorohexadecylhexyl)imidazolium 113 bis-1,3-(8-—(CH₂)₈— (CF₂)₁₁CF₃ —(CH₂)₈— (CF₂)₁₁CF₃perfluorododecyloctyl)imidazolium 114 1-(6-perfluorooctylhexyl)-3- —CH₂—H —(CH₂)₆— (CF₂)₇CF₃ methylimidazolium 115 1-(3-perfluorooctylpropyl)-3-—CH₂— H —(CH₂)₃— (CF₂)₇CF₃ methylimidazolium 1161-(6-perfluorobutylhexyl)-3- —CH₂— H —(CH₂)₆— (CF₂)₃CF₃methylimidazolium 117 1-(3-perfluoropentadecylpropyl)-3- —CH₂— H—(CH₂)₃— (CF₂)₁₄CF₃ methylimidazolium 1181-(3-perfluorooctadecylpropyl)-3- —CH₂— H —(CH₂)₃— (CF₂)₁₇CF₃methylimidazolium 119 1-(6-perfluorohexadecylhexyl)-3- —CH₂— H —(CH₂)₆—(CF₂)₁₅CF₃ methylimidazolium 120 1-(6-perfluorooctylhexyl)-3- vinyl H—(CH₂)₆— (CF₂)₇CF₃ vinylimidazolium 121 1-(3-perfluorooctylpropyl)-3-vinyl H —(CH₂)₃— (CF₂)₇CF₃ vinylimidazolium 1231-(6-perfluorobutylhexyl)-3- vinyl H —(CH₂)₆— (CF₂)₃CF₃ vinylimidazolium124 1-(3-perfluoropentadecylpropyl)-3- vinyl H —(CH₂)₃— (CF₂)₁₄CF₃vinylimidazolium 125 1-(3-perfluorooctadecylpropyl)-3- vinyl H —(CH₂)₃—(CF₂)₁₇CF₃ vinylimidazolium 126 1-(6-perfluorohexadecylhexyl)-3- vinyl H—(CH₂)₆— (CF₂)₁₅CF₃ vinylimidazolium

The compounds according to formula (1) can be prepared by any of thesynthetic methods known in the art. In a preferred embodiment, the ioniccompounds are prepared by reacting an imidazole with afluorohydrocarbon-containing halide. If a counteranion other than thehalide is desired, the resulting imidazolium halide can be reacted witha suitable compound capable of replacing the halide with anothercounteranion. For example, the synthesis may be practiced as follows:

In the above reaction scheme, the R group may be H, a hydrocarbon group,or a fluoro-substituted hydrocarbon group and R′ may be a hydrocarbon orfluoro-substituted hydrocarbon group such that the end product containsfluoro substitution. It is noteworthy that 1-methylimidazole (when R ismethyl) and 1-vinylimidazole (when R is vinyl) are particularlyavailable starting materials. The group X is typically a halide, but canbe other anionic atoms or groups that cause the R′ group to besufficiently electrophilic for reacting with an amine group. The solventis preferably a polar non-protic type of solvent such as acetonitrile.

In another aspect, the invention is directed to surface-functionalizedparticulate compositions. The particulate composition contains aparticulate having adhered to its surface a fluoroionic compound of thegeneral formula

The particulate compositions are useful for several purposes. Forexample, they can be incorporated into polymer compositions,particularly fluoropolymer compositions, to increase the thermalconductance and/or structural properties of the polymeric material. Theycan also function as electrolyte materials, and under the properconditions, as gas storage or microreaction vessel materials.

In formula (2), M represents a ring or ring system containing at leastone nitrogen atom in the ring or ring system. One or more ring nitrogenatoms can be substituted aside from the —(R^(a))_(v)—R^(b) groups by anyof the non-substituted or substituted hydrocarbon groups describedabove. Some examples of suitable nitrogen-containing rings includepyrrole, pyrrolidine, imidazole, 1-methylimidazole, pyrazole,piperidine, N-methylpiperidine, pyridine, piperazine,1-methylpiperazine, 1-phenylpiperazine, pyrazine, pyrimidine, andtriazine rings. Some examples of suitable nitrogen-containing ringsystems include indole, purine, benzimidazole, 4-(pyridin-4-yl)pyridine,bipyridine, and 1,8-naphthyridine ring systems.

The group R^(a) is a hydrocarbon linking group bound to a nitrogen atomof M and having at least one carbon atom, and optionally including oneor more non-fluoro heteroatoms or heteroatom-containing groups. Thesubscript v appended to R^(a) can assume a value of 0 or 1, therebyindicating whether R^(a) is absent or present, respectively. When R^(a)is not present, R^(b) is directly attached to a nitrogen atom of M. Allof the hydrocarbon linking groups already described above for R¹ and R³are applicable to R^(a) (i.e., R^(a) is aptly described by all of thehydrocarbon linking groups already described for R¹ and R³).

The group R^(b) is a fluoro-substituted hydrocarbon group having atleast one carbon atom and at least one fluorine atom and optionallyincluding one or more non-fluoro heteroatoms or heteroatom-containinggroups. All of the fluoro-substituted hydrocarbon groups alreadydescribed above for R² or R⁴ are applicable to R^(b) (i.e., R^(b) isaptly described by all of the fluoro-substituted hydrocarbon groupsalready described for R² or R⁴).

The subscript w is a positive integer representing the number of—(R^(a))_(v)—R^(b) units bound to an equal number of ring nitrogenatoms. More typically, w is a value of 1, 2, or 3. At least one of thering nitrogen atoms to which a —(R^(a))_(v)—R^(b) unit is bound ispositively charged.

The superscript +c represents a positive charge of magnitude c having avalue of at least 1 and equal to the number of ring nitrogen atoms boundto —(R^(a))_(v)—R^(b) units. More typically, c is a value of 1, 2, or 3.

The group X^(−r) represents an anion with negative charge −r, where r isa value of 1, 2, or 3. All of the applicable counteranions X havealready been described above. In order to preserve charge neutrality,the subscripts b and d are integers such that c×d=b×r.

In a preferred embodiment, the ionic compounds of formula (2) areaccording to the ionic compounds of formula (1), i.e., wherein M is animidazole ring containing either a hydrocarbon group, fluoro-substitutedhydrocarbon group, or a combination thereof bound to one of its ringnitrogen atoms, and a (R^(a))_(v)—R^(b) group bound to the othernitrogen atom of imidazole (i.e., w is 1). All of the fluoroioniccompounds already described above under formulas (1) and (3) areapplicable to the surface-functionalized particulate compositionsdescribed above.

In the particulate composition, the particles can be of any suitablecomposition depending on the application. For example, when used forimparting a higher thermal conductance to a material, the particles areselected based on their thermal conductive properties. The particles canbe composed of, for example, a metal or a main group element orcompound. The metal compositions include, for example, all of thetransition and rare earth metals. Some examples of metal compositionsinclude copper, bronze, aluminum, and nickel. Other elements, such asbarium and bismuth, can also be used as metals.

In one embodiment, the main group element or compound of the particlesis non-carbon based. Some examples of such compositions include theGroup III, V, and VII uncombined elements, as well as the oxide,sulfide, nitride, or phosphide compositions of these main groupelements. Some examples of main group compositions include silicon oxide(conventional glass), aluminum oxide, gallium nitride, boronitride,indium phosphide, tin oxide, tin sulfide, lead oxide, aluminumphosphide, and zinc phosphide. Alkali and alkaline earth compositionscan be suitable as well. These include, for example, magnesium oxide,calcium oxide, magnesium phosphide, calcium phosphide, lithium nitride,lithium oxide, and calcium sulfide. The particles can alternativelyinclude ionic salt structures, such as, for example, the metal sulfates(e.g., calcium sulfate (gypsum)), metal hydroxides, metal phosphates,metal carbonates, clays, and minerals.

In a preferred embodiment, the particles of the particulate compositionare carbon-based. By being carbon-based, the particles include carbonwithin their composition.

In one embodiment, the particles contain carbon combined with anotherone or more elements. Compositions containing carbon combined with oneor more other elements include the hydrocarbons and the carbides (e.g.,lithium carbide, calcium carbide, tungsten carbide, and aluminumcarbide).

In another embodiment, the particles contain predominantly or solelycarbon. All of the known allotropes of carbon are suitable for thisembodiment. In a particular embodiment, the composition is agraphene-containing composition, i.e., carbon-based unsaturatedcompositions containing conjugated sp²-hybridized carbon atoms engagedin carbon-carbon double bonds. Some examples of such carbon-basedmaterials include fibers, nanofibers, graphite, fullerenes, carbonnanotubes, carbon nanobuds, carbon nanohorns, and their combined forms.The graphene-containing particles can be of any suitable shape,including open or enclosed. Open carbon-based particles can be, forexample, curved, flat, or twisted. Some examples of enclosedcarbon-based particles include carbon nanotubes and fullerenes.

In a preferred embodiment, the particles are carbon nanotubes. As knownin the art, carbon nanotubes are enclosed and tubular in shape. They aretypically only a few nanometers in diameter (e.g., 1-20 nm) and can havevariable lengths of anywhere between nanometers to millimeters. Thecarbon nanotube can be any of the types of carbon nanotubes known in theart, including, for example, a single-walled carbon nanotube (SWNT orSWCNT), double-walled carbon nanotube (DWNT or DWCNT), or multiwalledcarbon nanotube (MWNT or MWCNT). A single-walled carbon nanotube canhave any suitable conformation, such as, for example, a zig zag mode(where m=0 of a n,m chiral vector), armchair mode (n=m), or chiral mode(all other chiral vector combinations). The synthesis of carbonnanotubes is well known in the art, and includes such methods as arcdischarge, laser ablation, and chemical vapor deposition (CVD).

The particles can be of any suitable size. For most applications, it ispreferable for the particles to be not more than micron-sized.Particularly when applying the particles as fillers for polymericmaterials, it is preferable for the particles to be not more than 1micron in any dimension. For example, the particles can have a sizerange of about 1 nm to 1 micron. In some embodiments, it may bepreferable to further limit the size to no more than 500 nanometers (nm)or 250 nm in any dimension. For example, the particles can have a sizerange in any dimension of about 1 nm to 500 nm or 1 nm to 250 nm. Inother embodiments, it may be preferable for the particles to be ofnanoscale dimension (nanoscopic), i.e., a dimension sufficiently smallthat the properties of an object of such dimensions are predominantlygoverned by the behavior of individual atoms. Typically, a nanoscopic ornanoscale object refers to an object having at least one dimensionwithin a range of about 1 to 100 nm.

The particles of the particulate composition are surface-functionalizedby having the fluoroionic compounds described above being adhered ontotheir surfaces. The ionic compounds are typically adhered by some formof electrostatic interaction. The electrostatic interaction can include,for example, a π-π interaction between the positively charged group ofthe ionic compound and carbon-carbon double bonds of a graphene lattice.

Any of the methods known in the art used in surface functionalization ofparticles can be applied herein. For example, in a preferred embodiment,the surface-functionalized particles are prepared by combining the ioniccompound and the particles, preferably with application of heat (as inmelt mixing), and then cooling and optionally grinding the cooledproduct into a powder.

In another aspect, the invention is directed to a fluorocompositematerial containing a fluoropolymer having incorporated therein any ofthe surface-functionalized particulate compositions described above. Thefluoroionic functionalization of the particles renders the particlesmore compatible, and thus, more dispersible and integratable with afluoropolymer. The particles, by virtue of their composition, can impartbeneficial properties to the fluoropolymer. Of primary relevance for thepurposes of this invention is an increased thermal conductivity.However, the functionalized particles can also impart an increasedmechanical strength, electrical conductivity, antistatic property,elasticity, and/or wear resistance.

Preferably, when the ionic liquids are used in the fluorocompositematerials, they have a decomposition temperature that is higher than theprocessing temperature of the fluoropolymer. The ionic liquids shouldalso have high enough temperature stability to withstand an extrusionprocess. For example, it may be preferable to use ionic liquids withdecomposition temperatures of at least, or above, 260° C. It is alsopreferable, where carbon nanoparticles, particularly carbon nanotubes,are used, that the ionic liquid have the ability to interactassociatively with the surface of the carbon nanoparticle or carbonnanotube. A preferred associative interaction is one which includes π-πinteractions between the electron-deficient cationic ring (e.g.,imidazolium or pyridinium ring) of the ionic liquid and the conjugatedgraphite surface of a carbon nanoparticle or nanotube. In addition, itis preferable that the ionic liquids contain sufficient fluorine atomsso that they are able to effectively disperse into the fluoropolymermatrix.

The fluoropolymer can be any of the fluoropolymers known in the art. Afluoropolymer is any polymer containing fluorine atoms. The mostpredominant are the fluoropolymers derived by addition polymerization offluoro-containing vinylic monomers. For example, the fluoropolymers canresult from the addition polymerization of one or more monomercompositions described by the following formula:

In formula (4), X₁, X₂, X₃, and X₄, can be, independently within amonomer and/or between different monomers represented by (4), a hydrogenatom, a fluorine atom, a chlorine atom, a group R representing ahydrocarbon group or a fluoro-substituted hydrocarbon group, or OR,wherein optionally, the hydrocarbon group or fluoro-substitutedhydrocarbon group R includes one or more heteroatoms orheteroatom-containing groups, provided that at least one monomer offormula (4) in the final addition polymer contain at least one fluorineatom. The terms “hydrocarbon group,” “fluoro-substituted hydrocarbongroup,” “heteroatoms,” and “heteroatom-containing groups” are as definedabove in the description provided for R² and R⁴.

The polymer resulting from one or more monomers of formula (4) can be ahomopolymer (i.e., containing only one type of formula (4) monomer), acopolymer (i.e., containing two distinct types of formula (4) monomers),a terpolymer (i.e., containing three distinct types of formula (4)monomers), or a higher multipolymer (i.e., containing more than threedistinct types of formula (4) monomers). As the groups of formula (4)have been defined, either all monomers of the resulting polymer arefluoro-substituted, or some of the monomers are fluoro-substituted whileothers are not fluoro-substituted. Accordingly, copolymers, terpolymers,and higher multipolymers derived from monomers of formula (4) cancontain non-fluorosubstituted monomer units, such as, for example,ethylene (—CH₂CH₂—), propylene (—CH(CH₃)CH₂—), chloroethylenes (e.g.,—CHClCH₂— or —CHClCHCl—), alkoxy-substituted ethylene (—CH(OR)CH₂—),methacrylic or methacrylate (e.g., —CH₂CH(C(O)OR)—), methylmethacrylicor methylmethacrylate (e.g., —CH₂CH(CH₃)(C(O)OR)—), vinylacetate, (e.g.,—CH₂CH(OC(O)R)—), where R is H or a non-fluoro substituted or completelyunsubstituted hydrocarbon as already defined above.

A copolymer, terpolymer, or higher multipolymer of the fluoropolymerscan have any of the forms known in the art, including having analternating, block, graft, or random arrangement of the monomer units.The invention also includes that monomer units can be linked by otherthan C—C bonds, such as, for example, ether (—C—O—C—), sulfur-containing(e.g., sulfonyl (—S(O)₂—) or —S—), nitrogen-containing (e.g., —NH—,—N(CH₃)— or —N═), and other heteroatom-containing bonds. Thefluoropolymers can also include heteroatom groups (e.g., pendant groups)that are not linking.

More typically, the fluoropolymer is formed by recurring units accordingto the formula

In formula (5), X₁, X₂, X₃, X₄, X₅, X₆, and X₇ can be, independentlywithin a recurring unit and between recurring units, a hydrogen atom, afluorine atom, chlorine atom, a group R representing a hydrocarbon groupcontaining 1 to 6 carbon atoms or a fluoro-substituted hydrocarbon groupcontaining 1 to 6 carbon atoms and at least one fluorine atom, or agroup —OR. Some examples of more typical hydrocarbon groups includemethyl, ethyl, n-propyl, and isopropyl. Some examples of more typicalfluoro-substituted hydrocarbon groups include trifluoromethyl,perfluoroethyl, and perfluoropropyl. Some examples of more typical ORgroups include methoxy, ethoxy, n-propoxy, isopropoxy, n-butoxy,isobutoxy, and t-butoxy.

In formula (5), the subscript f is a positive integer, and the subscriptg is 0 or 1, depending on whether the linking oxygen atom is absent orpresent, respectively. The subscript h is 0 or a positive integer. Inmore common embodiments, g is 0, f is 1, and h is 0 or 1. The polymercan contain any number of recurring units of formula (4) or (5).Typically, the polymer will contain at least about 10, 20, or 30recurring units and up to hundreds, thousands, or millions of recurringunits.

Some examples of common fluoropolymers include fluorinated ethylenepropylene (i.e., FEP, copolymer of tetrafluoroethylene (TFE) andhexafluoropropylene (HFP)), polytetrafluoroethylene (i.e., PTFE,homopolymer of TFE), the poly(perfluoroalkylvinylether)s (e.g., PFA andMFA), polyhexafluoropropylene (i.e., PHFP, homopolymer of HFP),polyhexafluoropropylene oxide (i.e., poly-HFPO or perfluoropolyether(PFPE) or perfluoroalkylether (PFAE) or perfluoropolyalkylether (PFPAE)having the general structure —(CF(CF₃)—CF₂—O)_(n)—),polychlorotrifluoroethylene (i.e., PCTFE, homopolymer ofchlorotrifluoroethylene, CTFE), polyvinylidene fluoride (i.e., PVDF,homopolymer of vinylidene fluoride, VDF (CH₂═CF₂)), a copolymer of PVDF(e.g., PVDF-TrFE where TrFE is trifluoroethylene, or PVDF-HFP),polyvinylfluoride (i.e. PVF, homopolymer of vinylfluoride, VF),poly(ethylene-tetrafluoroethylene), i.e., PETFE copolymer (copolymer ofethylene and TFE), poly(ethylene-chlorotrifluoroethylene), i.e., PECTFEpolymer (copolymer of ethylene and chlorotrifluoroethylene), THV (i.e.,terpolymer of TFE, HFP, and VDF), and homopolymers or copolymers ofperfluorobutylethylene (PFBE). These examples also include any of theircopolymers, or mixtures thereof, or combinations thereof.

The poly(perfluoroalkylvinylether)s (or perfluoroalkoxy polymers) are,generally, fluoropolymers that include fluoro-substituted monomer unitshaving one or more pendant alkoxy groups. More typically, these types ofpolymers contain at least one type of monomer unit of the type:

In formula (6) above, R represents a substituted or unsubstitutedhydrocarbon group as already previously described. More typically, R isa straight-chained or branched unsubstituted hydrocarbon having 1 to 6carbon atoms. Some examples of these types of fluoropolymers include PFA(a copolymer of perfluoropropylvinylether (PPVE) and TFE) and MFA (acopolymer of perfluoromethylvinylether (PPVE)).

Some trade name products of FEP include Neoflon™, Teflon®, Dyneon™,FluoroPlast™, and Dykor®. Some trade name products of PTFE includeFluon®, Algoflon®, Daikin-Polyflon™, Teflon®, Dyneon™, Heroflon™, andFluoroPlast™. Some trade name products of poly-HFPO include Krytox®.Some trade name products of PCTFE include Neoflon™. Some trade nameproducts of PVDF include Hylar®, Hylar 5000®, Kynar®, Kynar 500®, KynarFlex®, Solef PVDF®, and Dykor®. Some trade name products of PVF includeTedlar®. Some trade name products of PETFE include Aflon®, Neoflon™,Tefzel®, and Dyneon™. Some trade name products of PECTFE include Halar®.

The fluoropolymer composites can be prepared by any methods known in theart wherein the particulate can be integrally mixed or blended with thefluoropolymer. Typically, the fluoropolymer is a thermoplastic, thusrequiring that it be melted before or during a combining step with thesurface-functionalized particulate. The melted fluoropolymer having thesurface-functionalized particulate incorporated therein is typicallythen casted by cooling, thereby forming the fluoropolymer composite ofthe invention. However, the fluoropolymer need not be a thermoplasticsolid at ambient temperature, and hence, may not require a melting stepfor incorporating the surface-functionalized particulate. For example,the fluoropolymer can be in a sufficiently liquid state at ambienttemperature to permit mixing or blending of the particulate. The liquidfluoropolymer may be intended to remain in the liquid state or may beprocessed further to be casted, by, for example, heating. The finalsolid fluoropolymer can be a thermoplastic or thermoset.

In a further embodiment, the fluoropolymer composite containscrosslinked bonds. The crosslinked bonds can be between thefluoropolymer and particulate, or between fluoropolymer regions, orbetween particulates, or any combination thereof. The crosslinked bondscan be a result of crosslinking between any crosslinkable groupsresiding on either the particulate, the fluoropolymer, or both. Thecrosslinked bonds can be, for example, hydrocarbon linking groupsresulting from crosslinking of carbon-carbon double bonds (e.g., vinylicgroups). The crosslinking bonds can also include, for example, an amidogroup (e.g., by condensation of an amino group and carboxyl group), anester group (e.g., by condensation of a hydroxyl group with an ester orcarboxyl group), an ether group (e.g., by reaction of a glycidyl orother epoxy-containing group with a hydroxyl group, or by thecondensation reaction of hydroxyl groups with an aldehyde group), a ureagroup (e.g., by reaction of an isocyanate group with an amino group), acarbamate group (e.g., by reaction of an isocyanate group with ahydroxyl group), an imido group (e.g., by reaction of an amino groupwith an aldehyde or ketone), or a diazene group (e.g., by reaction of adiazonium salt with a nucleophilic aromatic group, such as phenol,anisole, or aniline).

The invention is also directed to a method for incorporatingcrosslinking into a fluoropolymer composite material. The methodincludes reacting crosslinkable groups residing on the fluoropolymerand/or surface of the particles of the particulate composition when boththe fluoropolymer and particulate composition are in a combined stateduring the reacting step.

In one embodiment, the crosslinkable groups are already present in thefluoropolymer and/or particles, thereby eliminating the need for afunctionalization step before the crosslinking reaction. In anotherembodiment, the fluoropolymer and/or particles require functionalizationwith crosslinkable groups before the crosslinking reaction.

The fluoropolymer can be functionalized with crosslinkable groups by anysuitable method known in the art. Some of these methods include theapplication of chemical grafting, radiation grafting, plasma grafting,ozonation grafting, and ultraviolet (UV) grafting.

In a preferred embodiment, the fluoropolymer is functionalized withcrosslinkable groups by radiation grafting. For example, thefluoropolymer can be irradiated by use of high energy radiation andgrafted with a compound containing carbon-carbon double bonds. Asubclass of these compounds can be conveniently described according toformula (7) below.R^(c)(CR₂)_(n)CH═CHR^(d)  (7)

In formula (7) above, R can be a hydrogen atom, fluorine atom, or any ofthe hydrocarbon groups, as previously defined, particularly according tothe description given for the groups represented by —R¹—R². Moretypically, R is H or F. The group R^(c) is a crosslinkable functionalgroup, such as, for example, an amino, vinyl, acyl chloride (e.g.,acryloyl chloride), carboxyl, hydroxyl, glycidyl or isocyanate group.The group R^(d) can be any of the groups as defined for R, but morepreferably represents a hydrogen, methyl, ethyl, propyl, isopropyl,n-butyl, isobutyl, methoxy, ethoxy or propoxy group. More preferably,R^(d) is a hydrogen atom. The subscript n can be any suitable value,preferably within the range of 1-20, more preferably 2-10, morepreferably 3-10, and even more preferably 6-8. The compound according toformula (7) will insert into the polymer through its carbon doublebonds, thereby exposing the R^(c) group.

In a preferred embodiment, R^(c) is an amino group or hydroxyl group andR^(d) is a hydrogen atom. The amino group can be used to crosslink withamino-reactive groups (e.g., an acyl chloride, acryloyl chloride,carbonyl, carboxyl, ester, or isocyanate group) residing on thefluoropolymer or particles. The hydroxyl group can be used to crosslinkwith hydroxyl-reactive groups (e.g., an acyl chloride, acryloylchloride, ester, carboxyl, or isocyanate group) residing on thefluoropolymer or particles. Alternatively, the amino or hydroxyl groupcan be further reacted with a chemical that will convert these groups,or link to these groups, to provide a different or modified reactivegroup. For example, the amino or hydroxyl group can be reacted withacryloyl chloride, thereby resulting in the conversion of these groupsto a vinyl-capped group. The vinyl-capped group can then be crosslinkedwith, for example, other vinylic groups residing on either thefluoropolymer or particles.

The particles of the particulate composition can also be functionalizedwith crosslinkable groups by any suitable method known in the art. Inone embodiment, the particles are functionalized with crosslinkablegroups by surface-functionalizing with one or more ionic compounds (suchas the fluoroionic compounds described above) that also contain acrosslinkable group. For example, the ionic compound can be avinyl-containing compound, such as the vinyl-containing ionic compounds55-63 or 120-126 shown in Table 1. The vinyl groups on the particles canbe made to crosslink with each other or with vinyl groups on thefluoropolymer, if present. In another embodiment, particles can befunctionalized by chemically attaching to the particles (e.g., bycovalent bond attachment) groups containing crosslinkable portionstherein. For example, it may be desirable for the particles to becovalently functionalized with crosslinkable groups and additionallyfunctionalized with fluoroionic compounds. In this manner, the particlesare capable of being crosslinked either with themselves or thefluoropolymer while also being readily dispersible within thefluoropolymer before crosslinking. It is also possible for acovalently-attached crosslinkable group to contain a fluoroioniccomponent.

In one embodiment, the crosslinking occurs between fluoropolymercrosslinkable and particulate crosslinkable groups. In anotherembodiment, the crosslinking occurs between fluoropolymer crosslinkablegroups. In yet another embodiment, the crosslinking occurs betweenparticulate crosslinkable groups. In still another embodiment, thecrosslinking occurs by a combination of the foregoing cros slinkingembodiments. For example, in one embodiment the crosslinking may occurbetween fluoropolymer segments and between fluoropolymer andparticulate, but not between particulate, whereas in another embodimentthe crosslinking may occur between fluoropolymer segments, and betweenparticulate, and between fluoropolymer and particulate.

Any method known in the art for inducing crosslinking can be usedherein. In one embodiment, crosslinking is induced by physical means.For example, in the case of crosslinking between vinylic groups, any ofthe suitable curing methods known in the art can be used. Some of thesecuring methods include application of ultraviolet (UV), high energyradiation, heat, plasma, or a combination thereof.

The opacity of carbon nanotubes may prevent radiation, such as UV, tocompletely penetrate into the fluoropolymer composite material. Thiswould lead to incomplete curing. Accordingly, in order to ensurecomplete curing, it is more preferable to use a combined UV and heatcuring process.

In another embodiment, crosslinking is induced by chemical means. Thechemical means may be a one-step process. For example, a crosslinkingreaction between an acyl chloride (e.g., acryloyl chloride) and amino orhydroxy crosslinkable groups can occur simply by contacting thecrosslinkable groups under suitable conditions known in the art.Alternatively, the crosslinking reaction (e.g., between carboxylic andamino crosslinkable groups) may require chemical activation means, byuse of a suitable activation group. Some activating groups particularlysuitable for activating amines and alcohols include, for example, theclass of carbodiimide compounds, such as DCC, DIC, and EDC. The chemicalactivation may also require the application of heat or radiation topromote the activation step.

In another embodiment, crosslinking can be induced between particles ofthe particulate composition when the particles are not combined with thefluoropolymer. The resulting crosslinked particulates can be useful inthemselves according to the uses described above for the functionalizedparticulate composition described above. Alternatively, the crosslinkedparticulates can be incorporated into the fluoropolymer by any of themeans described above. If desired, further crosslinking betweenfluoropolymer and particulate, or between fluoropolymer segments, canalso be made to occur.

In another aspect, the invention is directed to an article ofmanufacture constructed, at least in part, by the fluoropolymercomposite materials described above. The article, can be, for example, aprinting roller, tube, hose, sheet, fitted cover, protective cover,sleeve, film, block, ring, ball, part of an electrical component, orpart of a medical device.

Examples have been set forth below for the purpose of illustration andto describe the best mode of the invention at the present time. However,the scope of this invention is not to be in any way limited by theexamples set forth herein.

Example 1 Syntheses of Ionic Liquids

The reagents 3-(perfluorooctyl)propylamine, 3-(perfluorooctyl)propyliodide, 1-methylimidazole, 1-vinylimidazole, hexafluorophosphoric acid(60% water solution), and other reagents were obtained fromSigma-Aldrich Co. The ionic liquids IL-1 and IL-2 were synthesized usingthe general scheme shown in FIG. 1.

1. Synthesis of 1-(3-perfluorooctylpropyl)-3-methylimidazoliumhexafluorophosphate (IL-1) ionic liquid

Typically, 0.7 g (8.5 mmol) of 1-methylimidazole and 5.0 g (8.5 mmol) of3-(perfluorooctyl)propyl iodide were dissolved into 20 mL ofacetonitrile. The mixture was refluxed at 85° C. for 24 hours, andsubsequently cooled down to room temperature. The resulting samples werefiltered and washed with ethyl ether three times. The1-(3-perfluorooctyl)propyl-3-methylimidazolium iodide was obtained as awhite powder after being dried in a vacuum oven. The yield from thisreaction was about 90%.

Then 2.5 g (3.7 mmol) of 1-(3-perfluorooctyl)propyl-3-methylimidazoliumiodide was dispersed into 100 mL of water. To this, 0.7 mL (5.0 mmol) ofhexafluorophosphoric acid aqueous solution was slowly dropped into thesuspension under continuous stirring. The mixture was stirred for 24hours at room temperature. Methylene chloride was subsequently added toform a two-layer mixture, allowing the removal of the water layer. Afterevaporation, the white solid was washed with water until neutral. Thepowdery product was dried in a vacuum oven. The yield of this procedurewas about 95%.

2. Synthesis of 1-(3-perfluorooctyl)propyl-3-vinylimidazoliumhexafluorophosphate (IL-2) ionic liquid

An analogous procedure was followed to the synthesis above, except that1-vinylimidazole was used instead of 1-methylimidazole. The final yieldof this product was about 80%.

Example 2 Physical Modification of MWCNT with Ionic Liquids (Formationof iMWCNT)

A proportional mixture of IL-1 or IL-2 and oxidized MWCNT was melt mixedusing a twin-screw blender (DACA instruments) at 300 r/min for 2 min.After cooling, the blend yielded a solid material that was ground into apowder before using. A schematic representation of the π-stackingarrangement of ionic liquids on an MWCNT surface functionalized withionic liquids is shown in FIG. 2.

Example 3 Preparation of Nanocomposite Film Based on iMWCNT and FEP

The iMWCNT (modified by IL-1) was mixed with FEP powders using atwin-screw blender at 270° C. for 5-20 min. All samples weremelt-pressed at 270° C. into films with a thickness of about 0.1-0.5 mm.The composition of the nanocomposites is listed in Table 2 below. Thepreparation of iMWCNT/FEP nanocomposite is shown schematically in FIG.3.

TABLE 2 Nanocomposites of iMWCNT/FEP Nanocomposites Composition (weightratio) 1 FEP:MWCNT:IL-1 = 100:0.5:0.5 2 FEP:MWCNT:IL-1 = 100:0.5:5.0

Example 4 Chemical Grafting of a MWCNT for Introducing CrosslinkableGroups (Formation of gMWCNT)

The multiwall carbon nanotube (MWCNT) material was purchased fromNanostructured and Amorphous Materials, Inc. The diameter of the MWCNTwas about 8-15 nm. The as-received MWCNT sample was oxidized withconcentrated H₂SO₄/HNO₃ mixture (3:1) at 30° C. for 3 hours undermicrowave. The oxidized MWCNT was separated by washing with water,methanol (several times), and drying at 80° C. for 24 hours under vacuumafter filtration. The oxidized MWCNT was refluxed in thionyl chloridefor 24 hours at 65° C., and then the thionyl chloride was removed bydistillation.

The resulting dried acyl chloride-functionalized MWCNT can be combinedwith a fluoropolymer functionalized with crosslinkable groups reactiveto an acyl chloride (e.g., an amino group). Alternatively, the acylchloride-functionalized MWCNT can be further reacted with, for example,an amino-substituted vinylic compound to produce a vinyl-functionalizedMWCNT. The vinyl-functionalized MWCNT may be crosslinked with itself, oralternatively, or in combination, crosslinked with a fluoropolymer thathas been functionalized with vinylic groups, or other groups capable ofcrosslinking with the vinyl groups on the MWCNTs. FIG. 4 shows onepossible synthetic method for producing the acyl chloride MWCNT andfunctionalizing the MWCNT with a vinyl-capped amine to produce a MWCNTwith vinyl crosslinkable groups.

The dried acyl chloride MWCNT can also be reacted with a suitableend-functionalized fluoro-substituted compound to additionallyfunctionalize the carbon nanotube. For example, the dried acyl chlorideMWCNT was reacted with 3-perfluorooctylpropylamine in dry THF using TEAas a catalyst at 75° C. for two days. The chemical-grafted MWCNT(gMWCNT) was obtained by washing with water and THF and drying in vacuumat 70° C. One possible synthetic route for producing such achemical-grafted MWCNT is shown in FIG. 5.

Example 5 Chemical Modification and Functionalization of Fluoropolymersfor Introducing Crosslinkable Groups

Fluoro-ethylene-propylene copolymer (Teflon FEP100) was purchased fromDuPont, USA. FEP films were cut into pieces, packed, and sealed andirradiated on an aluminum tray by high energy radiation (e.g.,irradiated by an electron accelerator under air atmosphere and at roomtemperature where mean electron energy was about 1 MeV and the energydoses about 50 kGy). Immediately after the treatment, the films werecooled to −30° C. and stored for further use. The grafting reaction wascarried out in glass ampoules under nitrogen atmosphere.

1. The exposed samples were placed in reaction tubes containing afluoroalkenylamine (for example, a compound of general formulaH₂N(CF₂)—CH═CH₂, where n is any suitable integer, but particularly wheren=6 to 8), water, and ferrous sulfate as homopolymer initiator. Nitrogenwas bubbled through the solution to remove air from the tube. The tubeswere subsequently placed in a constant temperature water bath at 50° C.for a suitable period of time dependent on the thickness of the film,intensity of radiation, and other factors. The grafting time wastypically about 1 to 10 minutes, and more typically 1 to 5 minutes.After the grafting reaction, the samples were washed, purified, anddried under vacuum to a constant weight. The dried irradiated FEP filmwas then reacted with acryloyl chloride in an ice bath. Theradiation-grafted FEP film was obtained by washing with water and dryingunder vacuum at room temperature. The method is shown schematically inFIG. 6.

2. The exposed samples were placed in reaction tubes containing afluoroalkenylalcohol (for example, a compound of general formulaHO(CF₂)_(n)CH═CH₂, where n is any suitable integer, but particularlywhere n=6 to 8), water, and ferrous sulfate as homopolymer initiator.Nitrogen was bubbled through the solution to remove air from the tube.The tubes were subsequently placed in a constant temperature water bathat 50° C. for a suitable period of time dependent on the thickness ofthe film, intensity of radiation, and other factors. The grafting timewas typically about 1 to 10 minutes, and more typically 1 to 5 minutes.After the grafting reaction, the samples were washed, purified, anddried under vacuum to a constant weight. The dried irradiated FEP filmwas then reacted with acryloyl chloride in an ice bath. Theradiation-grafted FEP film was obtained by washing with water and dryingunder vacuum at room temperature. The method is shown schematically inFIG. 7.

Example 6 Preparation of Elastomeric Fluoropolymer Nanocomposites Basedon gMWCNT

An as-received oxidized MWCNT prepared by H₂SO₄/HNO₃ was refluxed withSOCl₂ to produce an acyl chloride-functionalized MWCNT. This was thenreacted with a fluoroalkenylamine, as described in Example 4 and FIG. 4.The final modified MWCNT contained vinyl groups, and could therefore, becrosslinked in the presence of initiators by application of heat and UVafter being melt-dispersed into the fluoropolymer matrix.

Fluoropolymer nanocomposite elastomer was prepared by a dualcross-linking system with UV and thermal curing process. A proportionalmixture of modified FEP, MWCNT, UV initiator and thermal initiator weremelt mixed using a twin-screw blender (DACA instruments) at 100° C. for20 min. Then the mixture was cured by UV radiation for 5 min and heattreated at 280° C. for another 10 min. A preferred physical process foraccomplishing this is shown in the process flow chart of FIG. 8. Atleast one possible chemical process by which the crosslinking occurs isshown in FIG. 9. The patterned lines in FIG. 9 represent associatedMWCNTs that have been functionalized with end-vinyl groups (as describedin Example 4 and FIG. 4) and blended into a vinyl-functionalized FEPfilm (as described in Example 5 and FIGS. 6 and 7).

Example 7 Preparation of Elastomeric Fluoropolymer Nanocomposites Basedon iMWCNT

The iMWCNT modified by IL-2 (the vinyl-containing fluoroionic liquiddescribed in Example 1 and FIG. 1) was mixed with modified FEP particlesand initiator using a twin-screw blender at 270° C. for 5-20 minutes.The vinyl group in IL-2 was polymerized at this condition and acrosslinked MWCNT framework was formed. This crosslinking improved theelastomeric properties of this nanocomposite. The composition of theelastomeric nanocomposites is listed in Table 3 below. One possiblemethod for producing an elastomeric fluoropolymer nanocomposite is shownin FIG. 10.

TABLE 3 Nanocomposite Elastomers of iMWCNT/FEP NanocompositesComposition (weight ratio) 3 FEP:MWCNT:IL-2:initiator = 100:0.5:0.5:0.54 FEP:MWCNT:IL-2:initiator = 100:0.2:2.0:0.5

Example 8 Preparation of Elastomeric Fluoropolymer Nanocomposites byChemical Crosslinking

Another way to produce the fluoropolymer elastomer in accordance withthe present invention is by chemical cross-linking of reactivecrosslinkable groups. In a preferred embodiment, the crosslinking wasaccomplished by crosslinking two kinds of modified carbon nanotubes(preferably MWCNTs) with different functional groups. The two types ofcarbon nanotubes were dispersed into modified FEP by melting extrusion,and then crosslinked by chemical reaction of the crosslinkable groups.The crosslinking step resulted in the formation of a crosslinkedframework of modified MWCNT in the FEP matrix. The resultingnanocomposite displayed an improved elastomeric property.

For example, FIG. 11 shows one possible method of chemical crosslinkingby crosslinking carbon nanotubes separately functionalized withcarboxylic acid and amino groups. From this reaction, amide crosslinkingbonds result. FIG. 12 shows another possible method of chemicalcrosslinking by crosslinking carbon nanotubes separately functionalizedwith carboxylic acid and hydroxyl groups. From this reaction, estercrosslinking bonds result.

It is important to note that crosslinking can also be made to occur byuse of any other suitable combinations of reactive groups, as describedabove, e.g., amino and ester, hydroxyl and ester, isocyanato andhydroxyl, amino and halide, hydroxyl and aldehyde or ketone, and so on.

While there have been shown and described what are presently believed tobe the preferred embodiments of the present invention, those skilled inthe art will realize that other and further embodiments can be madewithout departing from the spirit and scope of the invention describedin this application, and this application includes all suchmodifications that are within the intended scope of the claims set forthherein.

What is claimed is:
 1. A surface-functionalized particulate compositioncomprising a particulate having adhered to its surface an ionic compoundof the general formula

wherein: R³ is a hydrocarbon linking groups having at least one carbonatom, and optionally including one or more non-fluoro heteroatoms orheteroatom-containing groups; —R¹—R² represents a vinyl group R⁴ is afluoro-substituted hydrocarbon group having at least one carbon atom andat least one fluorine atom and optionally including one or morenon-fluoro heteroatoms or heteroatom-containing groups; the subscripts mand p are independently 0 or 1, where a value of 0 for a subscriptrepresents the absence of a group to which the subscript is appended,and a value of 1 represents the presence of a group to which thesubscript is appended; X^(−r) represents an anion with negative charge−r, where r is a value of 1, 2, or 3; and the subscripts a and b arepositive integers such that a=b×r; wherein m is
 1. 2. The particulatecomposition of claim 1, wherein the particulate composition is agraphene-containing composition.
 3. The particulate composition of claim2, wherein the particulate is selected from graphene sheets, graphitenanoparticles, carbon nanotubes, fullerenes, carbon nanohorns, carbonfibers, carbon nanofibers, carbon nanobuds, and combinations thereof. 4.The particulate composition of claim 3, wherein p is
 1. 5. Theparticulate composition of claim 4, wherein R³ is a hydrocarbon linkinggroup having 1 to 6 carbon atoms.
 6. The particulate composition ofclaim 5, wherein R⁴ is a fluoro-substituted hydrocarbon group having 1to 30 carbon atoms and at least one fluorine atom.
 7. The particulatecomposition of claim 6, wherein all hydrogen atoms of R⁴ are substitutedby fluorine atoms.
 8. The particulate composition of claim 7, wherein R⁴contains 4 to 12 carbon atoms.
 9. The particulate composition of claim7, wherein R⁴ contains 6 to 10 carbon atoms.
 10. Asurface-functionalized particulate composition comprising a carbon-basedparticulate having adhered to its surface an ionic compound of thegeneral formula

wherein: R³ is a hydrocarbon linking groups having at least one carbonatom, and optionally including one or more non-fluoro heteroatoms orheteroatom-containing groups; —R¹—R² represents a vinyl group; R⁴ is afluoro-substituted hydrocarbon group having at least one carbon atom andat least one fluorine atom and optionally including one or morenon-fluoro heteroatoms or heteroatom-containing groups; the subscripts mand p are independently 0 or 1, where a value of 0 for a subscriptrepresents the absence of a group to which the subscript is appended,and a value of 1 represents the presence of a group to which thesubscript is appended; X^(−r) represents an anion with negative charge−r, where r is a value of 1, 2, or 3; and the subscripts a and b arepositive integers such that a=b×r.
 11. A surface-functionalizedparticulate composition comprising a carbon-based particulate havingadhered to its surface an ionic compound of the general formula

wherein: R³ is a hydrocarbon linking group having 1 to 6 carbon atoms;R⁴ is a fluoro-substituted hydrocarbon group having 1 to 30 carbon atomsand at least one fluorine atom; R⁵ represents a vinyl group; X^(−r)represents an anion with negative charge −r, where r is a value of 1, 2,or 3; and the subscripts a and b are positive integers such that a=b×r.12. The particulate composition of claim 11, wherein R⁴ contains 4 to 12carbon atoms and at least one fluorine atom.
 13. The particulatecomposition of claim 11, wherein R⁴ contains 6 to 10 carbon atoms and atleast one fluorine atom.
 14. An article of manufacture comprising anarticle constructed of a material comprising a fluoropolymer compositematerial comprising a fluoropolymer having incorporated therein asurface-functionalized particulate composition comprising a particulatehaving adhered to its surface an ionic compound of the general formula

wherein: R³ is a hydrocarbon linking groups having at least one carbonatom, and optionally including one or more non-fluoro heteroatoms orheteroatom-containing groups; —R¹—R² represents a vinyl group; R⁴ is afluoro-substituted hydrocarbon group having at least one carbon atom andat least one fluorine atom and optionally including one or morenon-fluoro heteroatoms or heteroatom-containing groups; the subscripts mand p are independently 0 or 1, where a value of 0 for a subscriptrepresents the absence of a group to which the subscript is appended,and a value of 1 represents the presence of a group to which thesubscript is appended; X^(−r) represents an anion with negative charge−r, where r is a value of 1, 2, or 3; and the subscripts a and b arepositive integers such that a=b×r.
 15. The article of manufacture ofclaim 14, wherein the article of manufacture is either a printingroller, tube, hose, sheet, fitted cover, protective cover, sleeve, film,block, ring, ball, part of an electrical component, or part of a medicaldevice.
 16. An article of manufacture comprising an article constructedof a material comprising a fluoropolymer composite material comprising afluoropolymer having incorporated therein a surface-functionalizedparticulate composition comprising a particulate having adhered to itssurface an ionic compound of the general formula

wherein: R³ is a hydrocarbon linking group having 1 to 6 carbon atoms;R⁴ is a fluoro-substituted hydrocarbon group having 1 to 30 carbon atomsand at least one fluorine atom; R⁵ represents a vinyl group; X^(−r)represents an anion with negative charge −r, where r is a value of 1, 2,or 3; and the subscripts a and b are positive integers such that a=b×r.